Theoretical study of surface plasmons coupling in transition metallic alloy 2D binary grating

• The excitation of a surface plasmon polariton (SPP) is numerically investigated.
• The SPR coupling system consisted of homogeneous alloys of two or three metals.
• The addition of 25% of Al to two metals alloy is insufficient to change the curves.
• The influence of grating parameters is discussed in details (RCWA) method.
• dx=dy=700 nm, h=40 nm and w=0.5 are the optimal parameters for exciting SPP.

The excitation of a surface plasmon polariton (SPP) wave on a metal–air interface by a 2D diffraction grating is numerically investigated. The grating consists of homogeneous alloys of two metals of a formula AxB1−x, or three metals of a formula AxByCz, where A, B and C could be silver (Ag), copper (Cu), gold (Au) or aluminum (Al).It is observed that all the alloys of two metals present a very small change of surface plasmon resonance (SPR) irrespective of composition x. Moreover, the addition of 25% of Al to two metals alloy is insufficient to change the SPR curves. The influence of the different grating parameters is discussed in details using rigorous coupled-wave analysis (RCWA) method. Furthermore, the SPR is highly dependent on grating periods (dx and dy) and the height of the grating h. The results reveal that dx= dy= 700 nm, h=40 nm and duty cycle w=0.5 are the optimal parameters for exciting SPP.